Acceptor-Connector pattern
Acceptor-Connector pattern is described by Douglas C. Schmidt in three papers: Acceptor, A Design Pattern for Passively Initializing Network Services; Connector, A Design Pattern for Actively Initializing Network Services and Acceptor-Connector, An Object Creational Pattern for Connecting and Initializing Communication Services. An overview with examples in C++/Poco is provided.
/*
Acceptor.cpp
------------
Use of the Acceptor design pattern.
Compile with
g++ -I /usr/local/poco-1.4.2p1-all/include/ -L /usr/local/poco-1.4.2p1-all/lib -lPocoFoundation -lPocoNet -oAcceptor Acceptor.cpp
*/
#include <cstdlib>
#include <iostream>
#include <string>
#include <Poco/Timespan.h>
#include <Poco/Thread.h>
#include <Poco/NObserver.h>
#include <Poco/Net/SocketReactor.h>
#include <Poco/Net/ServerSocket.h>
#include <Poco/Net/StreamSocket.h>
#include <Poco/Net/SocketAcceptor.h>
#include <Poco/Net/SocketNotification.h>
using std::cout;
using std::endl;
using std::string;
using Poco::AutoPtr;
using Poco::Timespan;
using Poco::Thread;
using Poco::NObserver;
using Poco::Net::SocketReactor;
using Poco::Net::ServerSocket;
using Poco::Net::StreamSocket;
using Poco::Net::SocketAcceptor;
using Poco::Net::SocketNotification;
using Poco::Net::ReadableNotification;
using Poco::Net::WritableNotification;
// handles communication and service logic
class ServiceHandler
{
public:
ServiceHandler(StreamSocket socket, SocketReactor& reactor) : _socket(socket), _reactor(reactor)
{
}
void onReadable(const AutoPtr<ReadableNotification>& notification)
{
char buf[100];
int no = _socket.receiveBytes(buf, 99);
if (no > 0)
{
buf[no] = '\0';
cout << "ServiceHandler::onReadable(): buf=" << buf << endl;
_request = buf;
}
else
{
// destroy handlers
cout << "ServiceHandler::onReadable(): destroying handlers" << endl;
_reactor.removeEventHandler(_socket, NObserver<ServiceHandler, ReadableNotification>(*this, &ServiceHandler::onReadable));
_reactor.removeEventHandler(_socket, NObserver<ServiceHandler, WritableNotification>(*this, &ServiceHandler::onWritable));
_socket.close();
delete this;
}
}
void onWritable(const AutoPtr<WritableNotification>& notification)
{
if (!_request.empty())
{
cout << "ServiceHandler::onWritable(): _request=" << _request << endl;
_socket.sendBytes(_request.c_str(), _request.length());
_request.clear();
}
}
private:
StreamSocket _socket;
SocketReactor& _reactor;
string _request;
};
class ServiceInitializer
{
public:
ServiceInitializer(StreamSocket& socket, SocketReactor& reactor) : _socket(socket), _reactor(reactor)
{
cout << "ServiceInitializer::ServiceInitializer(): client accepted" << endl;
ServiceHandler* handler = new ServiceHandler(_socket, _reactor);
_reactor.addEventHandler(_socket, NObserver<ServiceHandler, ReadableNotification>(*handler, &ServiceHandler::onReadable));
_reactor.addEventHandler(_socket, NObserver<ServiceHandler, WritableNotification>(*handler, &ServiceHandler::onWritable));
}
~ServiceInitializer()
{
cout << "ServiceInitializer::~ServiceInitializer():" << endl;
}
private:
StreamSocket _socket;
SocketReactor& _reactor;
};
int main()
{
ServerSocket socket(9000);
SocketReactor reactor(Timespan(0, 0, 0, 1, 0));
SocketAcceptor<ServiceInitializer> acceptor(socket, reactor);
Thread thread;
thread.start(reactor);
thread.join();
return EXIT_SUCCESS;
}
/*
Connector.cpp
-------------
Use of the Connector design pattern.
Compile with
g++ -I /usr/local/poco-1.4.2p1-all/include -L /usr/local/poco-1.4.2p1-all/lib/ -lPocoFoundation -lPocoNet -oConnector Connector.cpp
*/
#include <cstdlib>
#include <iostream>
#include <string>
#include <Poco/Timespan.h>
#include <Poco/Thread.h>
#include <Poco/NObserver.h>
#include <Poco/Net/SocketAddress.h>
#include <Poco/Net/StreamSocket.h>
#include <Poco/Net/SocketReactor.h>
#include <Poco/Net/SocketConnector.h>
#include <Poco/Net/SocketNotification.h>
using std::cout;
using std::endl;
using std::string;
using Poco::AutoPtr;
using Poco::Timespan;
using Poco::Thread;
using Poco::NObserver;
using Poco::Net::SocketAddress;
using Poco::Net::StreamSocket;
using Poco::Net::SocketReactor;
using Poco::Net::SocketConnector;
using Poco::Net::SocketNotification;
using Poco::Net::ReadableNotification;
using Poco::Net::WritableNotification;
// handles communication and service logic
class ServiceHandler
{
public:
ServiceHandler(StreamSocket socket, SocketReactor& reactor) : _socket(socket), _reactor(reactor)
{
}
void onWritable(const AutoPtr<WritableNotification>& notification)
{
string request = "Hello, World!";
_socket.sendBytes(request.c_str(), request.length());
}
void onReadable(const AutoPtr<ReadableNotification>& notification)
{
char buf[100];
int no = _socket.receiveBytes(buf, 99);
if (no > 0)
{
buf[no] = '\0';
cout << "ServiceHandler::onReadable(): buf=" << buf << endl;
}
else
{
// destroy handlers
cout << "ServiceHandler::onReadable(): destroying handlers" << endl;
_reactor.removeEventHandler(_socket, NObserver<ServiceHandler, ReadableNotification>(*this, &ServiceHandler::onReadable));
_reactor.removeEventHandler(_socket, NObserver<ServiceHandler, WritableNotification>(*this, &ServiceHandler::onWritable));
_socket.close();
delete this;
}
}
private:
StreamSocket _socket;
SocketReactor& _reactor;
};
class ServiceInitializer
{
public:
ServiceInitializer(StreamSocket socket, SocketReactor& reactor) : _socket(socket), _reactor(reactor)
{
cout << "ServiceInitializer::ServiceInitializer():" << endl;
ServiceHandler* handler = new ServiceHandler(_socket, _reactor);
_reactor.addEventHandler(_socket, NObserver<ServiceHandler, WritableNotification>(*handler, &ServiceHandler::onWritable));
_reactor.addEventHandler(_socket, NObserver<ServiceHandler, ReadableNotification>(*handler, &ServiceHandler::onReadable));
}
~ServiceInitializer()
{
cout << "ServiceInitializer::~ServiceInitializer():" << endl;
}
private:
StreamSocket _socket;
SocketReactor& _reactor;
};
int main()
{
SocketAddress address("localhost:9000");
SocketReactor reactor(Timespan(0, 0, 0, 1, 0));
SocketConnector<ServiceInitializer> connector(address, reactor);
Thread thread;
thread.start(reactor);
thread.join();
return EXIT_SUCCESS;
}
